1. Field of the Invention
This invention relates to a method and apparatus for controlling ignition timing to accommodate variations in load and speed changes and ambient conditions, and more particularly to a method and apparatus that achieves the foregoing by adjusting the angular position of spark ignition to maintain substantially constant the angular position of peak cylinder pressure.
2. Description of the Prior Art
The effect of humidity changes on optimum spark timing is discussed in Nakajima, K., K. Shinoda, and K. Onoda, "Experiments on Effects of Atmospheric Conditions on the Performance of an Automotive Gasoline Engine," SAE paper 690166 and Gardiner, A. W., "Atmospheric Humidity and Engine Performance," SAE Trans., Vol. 24 (1929).
The effect of altitude changes on optimum spark timing is disclosed by Hubbard, M., "Applications of Automatic Control to Internal Combustion Engines," Ph.D. Dissertation, Guidance & Control Lab., Stanford University, Stanford, California 1975. Other efforts to control ignition timing in accordance with variations in power demands and ambient conditions have been disclosed in the following references:
Draper, C. D., and Y. T. Li, "Principles of Optimalizing Control Systems and an Application to the Internal Combustion Engine." ASME Publication, Sept. 1951. PA0 Schweitzer, P. H., C. Volz, and F. DeLuca, "Control System to Optimize Engine Power," SAE paper 660022. PA0 Schweitzer, P. H., and C. Volz, "Electronic Optimizer Control for Internal Combustion Engines," SAE Paper No. 750370, Feb. 1975.